1. Field of the Invention
This disclosure relates to a liquid discharge head configured to discharge liquid and a liquid discharge apparatus.
2. Description of the Related Art
Ink (liquid) is supplied from an ink tank in which the ink is stored to an ink jet recording head (liquid discharge head) to be mounted on an ink jet recording apparatus (hereinafter, also referred to as a recording apparatus) representative as a liquid discharge apparatus. Japanese Patent Laid-Open No. 2002-144605 describes a configuration in which ink supplied from an ink tank passes through a flow channel provided in a flow channel member and is supplied to an ink discharge portion.
In order to eliminate time and labor of a user for mounting the ink jet recording head on the recording apparatus, there is a case where the recording apparatus is shipped in a state in which the ink jet recording head is mounted. In order to prevent ink from being leaked during transportation, the ink jet recording head is kept empty without being filled with ink when being transported. Then, at the beginning of usage of the recording apparatus, ink is sucked from an ink discharge portion of the ink jet recording head and the interior of the ink jet recording head is initially filled with ink. At this time, since the flow channel in the empty state has a dry inner wall, the ink can hardly be adapted well to the inner wall, so that the following problems may occur at a bent portion of the flow channel.
In other words, as illustrated in FIG. 8 of Japanese Patent Laid-Open No. 2002-144605, in the flow channel provided with a bent portion, separation of a boundary layer may occur when being initially filled with ink in the bent portion, and an air bubble may be generated and stay thereon. If the air bubble stays in the interior of the ink jet recording head, there is a risk of printing failure due to insufficient supply of ink to an ink discharge portion.
The probability of occurrence of separation of the boundary layer is increased with increase in flow speed of the ink when sucking the ink. Therefore, the problem of stay of the air bubble is improved to some extent by a method of lowering the flow speed as much as possible. However, if the sucking speed is low, waiting time until the apparatus becomes available for printing at the beginning of use becomes long.